[T3] '72 FI into a '71

Jim Adney jadney at vwtype3.org
Sun Sep 21 15:10:18 PDT 2014


On 21 Sep 2014 at 13:37, Brandon Bacod wrote:

> What pitfalls might one run in to trying to install a '72 FI engine into a
> '71 which has apparently has had all of the FI harnesses stripped out?
> Bought a '72 with seemingly all of the engine there. Fuel pump in unknown
> condition, from what I can tell the decel valve and a bunch of relays are
> all hooked up, but the PO had a long story of his tweaker friend goofing
> off with it, and when it came to me it came without a generator, a couple
> plug wires and coil, so obviously it wouldn't run. Now. How difficult will
> it be to transplant all of the various relays/how essential are they? I've
> sat down with my Bentley in an attempt to get it running, but certain wires
> just don't seem to be diagrammed, and I don't want to sink a bunch of time
> into it if it's a doomed swap.

The '72 FI is an odd year, so this would only work if you swapped 
EVERYTHING in the engine compartment: brain, distributor, intake air 
distributor. Even the tranny is slightly different, with an extra 
switch on it, but you can ignore that and plumb the vacuum advance 
directly to the IAD, like all the other years.

'71 is one of the best FI years, while '72 is one of the worst, 
simply from a tuneup/maintenance perspective. If you have any of the 
old '71 FI parts, I'd try to resurrect the '71 FI. Otherwise, look 
for a '68-71 donor car. I realize this will be hard if you aren't 
already familiar with our FI. 

FYI, the '71 and '72 FI wiring harnesses are different. You would 
need a harness from a '70 or '71 to work with the '71 FI.

> Compression test shows ~125 lbs on 2,3,4 but only 40 on 1...

40 sounds so low that it makes me wonder if there's something simple 
wrong, like rust on a valve seat, a sticky valve, or .... It would be 
unusual for a #1 valve to burn, but it's not impossible.

Pull off the rocker assy on that side and see if the head studs below 
#1 hold torque. They may be pulling out of the case, which would be a 
bad sign, but it's likely that there is a simple solution here.

-- 
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Jim Adney, jadney at vwtype3.org
Madison, Wisconsin, USA
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